a) Field of the Invention
The invention relates to a toothed rack or threaded rod, in particular for a steering mechanism for a motor vehicle, which comprises a first rod-shaped part which, as a function element of the toothed rack or threaded rod, comprises at least one element for the conversion of a rotational movement into a translational movement, in particular a toothing and/or threading for the engagement of a threaded nut or of a threaded drive, and a second rod-shaped part which is connected with the first rod-shaped part and which preferably comprises at least one further function element of the toothed rack or of the threaded rod. The first and the second rod-shaped parts each has a hollow volume opening out at one connection end of the particular rod-shaped part and the connection of the first with the second rod-shaped part takes place via a separate connection part having first and second connection pins. The first connection pin is held by press fit in the hollow volume, opening out at the connection end, of the first rod-shaped part and the second connection pin is held by press fit in the hollow volume, opening out at the connection end, of the second rod-shaped part.
b) Description of Related Prior Art
Toothed racks or threaded rods, for example toothed racks or threaded rods employed in steering mechanisms of motor vehicles, conventionally comprise several function regions each forming a section of the longitudinal dimension of the toothed rack or threaded rod. One function region serves for converting the rotational movement, such as is introduced by a steering wheel of a motor vehicle into a steering system, into a translational movement, such as is required in this example for turning the wheels of the motor vehicle. For this purpose one function region includes as a function element at least one toothing and/or threading for the engagement of a threaded nut, in particular a ball-type threaded nut, or of a threaded drive, in particular a ball-type threaded drive. At its ends in the axial direction the toothed rack or threaded rod comprises function elements for securing in position elements connected with the wheel, for example the tie rods. In a further function region, for example in addition to a toothing in the first function region, a threading, for example for a ball-type threaded gear, can further be provided in order to implement a threaded drive by means of a nut disposed on this threading. This threaded gear can be utilized for a power assistance of the steering movement. The toothed rack or threaded rod can, instead, also comprise in at least one further function region other types of function elements. For example, at one rod section of the toothed rack or threaded rod a piston for a power assistance of the steering can be provided or form elements for securing such in position. As such, a function region can also be a smooth rod section serving for the axial guidance of the toothed rack or threaded rod, which rod section forms a bearing face. For the implementation of the several function elements, different fabrication steps must be completed in the production of the toothed rack or threaded rod.
To make possible better adaptation to the implementation of the individual function region, toothed racks are already known in which a first and a second rod-shaped part, each of which includes a function element of the toothed rack, are connection with one another. Apart from known welding of these two rod-shaped parts, WO 2006/066309 A1 also discloses a bolted connection of the two rod-shaped parts. A connection pin disposed on one part is herein provided with outer threads and is screwed into inner threads of an axial hollow volume, receiving the connection pin, of the other rod-shaped part. To secure this bolted connection serves in one embodiment an adhesive agent. In another embodiment example the wall encompassing the hollow volume receiving the pin is pressed at one site into an indentation of the pin. While through this implementation of the toothed rack with the division of the toothed rack into two or several rod-shaped parts having function regions, facilitation and improvement in the production is attained compared to the implementation of the toothed rack in one piece, the described bolted connection, however, also entails disadvantages, inter alia corresponding production expenditures and restrictions with respect to the implementation of the parts to be connected.
A device of the above described type is evident in the not prior published DE 10 2007 018 919 A1. To connect the first and second rod-shaped parts, a connection part is provided which includes first and second connection pins, each of which is held through a press fit in a hollow volume of the particular rod-shaped part. Through the press fit of the connection part with the particular rod-shaped part a reliable connection can be achieved between the first and the second rod-shaped part.